Conventionally, a solid preparation printing apparatus (tablet printing apparatus) described in Patent Literature 1 has been known. The solid preparation printing apparatus includes a printer, which performs printing (transfer) by a transfer roller, and the printer performs printing of characters, marks and the like on surfaces of solid preparations (tablets) sequentially conveyed by a conveyor (conveyor belt). In the conveyor, pockets having a minute hole are arranged in the conveying direction of the conveyor. With the movement of the conveyor with solid preparations accommodated in the pockets of the conveyor, the solid preparations are sequentially conveyed. An air suction part, which sucks air through the minute hole formed in each pocket, is disposed on the back side of a portion of the conveyor which opposedly faces the transfer roller. By an air suction effect of the air suction part, the solid preparation accommodated in each pocket is fixed in the pocket at the portion of the conveyor opposedly facing the transfer roller. By fixing the solid preparation as described above, the transfer roller can transfer (print) characters, marks and the like on the solid preparation accommodated in each pocket without misalignment. Then, an ink transferred to surfaces of respective solid preparations is dried by a hot air dryer disposed on the downstream side of the printer in the conveying direction along which solid preparations are conveyed.
By taking into account ease of changing characters or marks, and hygiene, an ink ejection printer (so-called inkjet printer), which performs printing in a non-contact manner, may be used in place of a printer using the transfer roller. The inkjet printer includes an inkjet head equipped with a plurality of nozzles for ejecting ink droplets. The inkjet printer ejects ink droplets from the plurality of nozzles of the inkjet head in accordance with a pattern based on printing data thus performing printing on a surface of a tablet.